1. Filed of the Invention
The present invention relates to a memory card adaptor which enables a small memory card to be used in a card connector for a large memory card that is larger than the small memory card.
2. Description of the Prior Art
Conventionally, as a downsized version of an SD card (24×32×2.1 mm: length×width×thickness), a mini SD card (20×21.5×1.4 mm: length×width×thickness) 200 such as shown in FIGS. 9A, 9B, and 9C has been provided.
As shown in FIGS. 9A, 9B, and 9C, in the rear face side of an end portion of the front side of the mini SD card 200 in the case where the mini SD card is inserted in the normal insertion posture (hereinafter, the front side in this case is referred to as “rear side”), eleven contacts 204a to 204k are juxtaposed in a direction (hereinafter, referred to as “lateral direction”) which is perpendicular to the longitudinal direction and the thickness direction. In the rear side of the mini SD card 200, a cut-away portion 201 is formed by cutting away one edge. A step portion 202 which is upward directed is formed in each of the right and left side edges of the surface side of the rear end portion of the mini SD card 200 in which the width is narrowed by the cut-away portion 201. The cut-away portion 201 cooperates with the step portions 202 to prevent erroneous insertion of the mini SD card 200 into a card connector in a posture other the normal insertion posture (insertion in a posture where the front and rear relationship and the front and back relationship are inverted) from occurring. A locking cut-away 203 is disposed in each of the right and left sides of the surface of the mini SD card 200 in a wider portion which is in front of the step portions 202, so that, when the mini SD card 200 is attached to the card connector, locking members of the card connector are engaged with the locking cut-aways 203, thereby preventing the mini SD card 200 from dropping off. In the eleven contacts 204a to 204k of the mini SD card 200, the first to eleventh contacts 204a to 204k are sequentially arranged in a direction from left to right as seen from the side of the rear face, four or the first, second, tenth, and eleventh contacts 204a, 204b, 204j, 204k are used for data, the third contact 204c is used for a command, two or the fourth and ninth contacts 204d, 204i are used for grounding, the seventh contact 204g is used for power supply, and the eighth contact 204h is used for a clock signal. The two or the fifth and sixth contacts 204e, 204f are preliminarily added to the mini SD card 200. The effective contacts are nine so as to correspond to the nine contacts of the SD card.
Recently, as a memory card which is smaller than the mini SD card 200, a TransFlash card, and a micro SD card (11×15×1 mm: length×width×thickness) 300 such as shown in FIGS. 10A, 10B, and 10C in which the TransFlash specification is adopted have been provided.
As shown in FIGS. 10A, 10B, and 10C, in the rear side of the micro SD card 300, a cut-away portion 301 is formed by cutting away one edge. A locking cut-away 302 is disposed in one side portion of the micro SD card 300 on the side of the cut-away portion 301 and in a wider portion which is in front of the cut-away portion 301. In the rear face side of an end portion of the rear side of the micro SD card 300, eight contacts 303a to 303h are juxtaposed in the lateral direction. In the eight contacts 303a to 303h of the micro SD card 300, the first to eighth contacts 303a to 303h are sequentially arranged in a direction from left to right as seen from the side of the rear face, four or the first, second, seventh, and eighth contacts 303a, 303b, 303g, 303h are used for data, the third contact 303c is used for a command, the fourth contact 303d is used for power supply, the fifth contact 303e is used for a clock signal, and the sixth contact 303f is used for grounding. In the micro SD card 300, namely, the grounding contact is reduced to one, and the number of contacts is reduced to eight as compared with the case where an SD card and the mini SD card 200 have the nine contacts (in the mini SD card 200, the number of effective contacts).
As described above, as compared with the mini SD card 200 in the conventional art, the micro SD card 300 is slightly smaller in outer dimensions, and has the fewer number of contacts. In order to use the micro SD card in a conventional card connector for a mini SD card, therefore, a memory card adaptor for this purpose is required. A memory card adaptor of this kind is disclosed by, for example, Japanese Utility Model Registration No. 3,110,839.
The conventional memory card adaptor which enables a micro SD card to be used in a card connector for a mini SD card is configured in the following manner. The adaptor comprises a mini-SD card type adaptor body which is formed so as to have outer dimensions corresponding to the mini SD card specification, and to which a micro SD card is to be attached. In the adaptor body, eleven stationary terminals which are to be electrically connected to eleven contacts of the card connector, and eight movable terminals which are to be electrically connected to the eight contacts of the micro SD card are separately disposed. The eight movable terminals are electrically connected to the corresponding eight stationary terminals via a circuit board disposed in the adaptor body, respectively, and the two grounding stationary terminals are electrically connected to each other.
As described above, the conventional memory card adaptor incorporates the circuit board, and includes the two kinds of terminals, or the terminals which are to be connected to a card connector for a large memory card, and those which are to be connected to a small memory card. Therefore, the conventional memory card adaptor has problems in that the number of the components is large, that the structure is complicated, and that the production cost is high. In the adaptor body, the circuit board exists over the range from the front end to the rear end. Consequently, metal components cannot be used in the adaptor body, and there arises a further problem in that it is impossible to take a countermeasure against electrostatic breakdown.
A technique in which, in a memory card adaptor, one of components of an adaptor body is made of a metal, and the metal component is electrically connected to plural grounding contacts incorporated in the adaptor body to take a countermeasure against electrostatic breakdown is disclosed by, for example, Japanese Patent Application Laying-Open No. 2004-272704. When this conventional well-known technique is employed, it is not required to, as in the conventional memory card adaptor, incorporate a circuit board, and separately dispose two kinds of terminals, or terminals which are to be connected to a card connector for a large memory card, and those which are to be connected to a small memory card. Therefore, the number of components is small, the structure is simplified, and the production cost can be reduced.